1. Field of the Invention
The present invention relates to methods for treating wood and other porous, flammable materials to provide fire retardancy and also relates to methods designed to preserve these materials against termites, rot, insects and marine borers.
2. Description of the Prior Art
Wood and wood products, such as pressed board, cardboard, boxboard and the like, are presently subjected to a variety of prior art techniques to provide preserving characteristics against environmental and insect damage. To this end, chemicals such as creosote, copper naphthenate, pentachlorophenol, and chromated copper arsenate as well as others are applied to the wood surface. In some cases, the treating chemical is driven into the voids of the wood material by heat or pressurization, or both.
Additionally, wood and wood products have been subjected to prior art techniques for imparting some degree of fire retardancy to those materials. With respect to the use of those preserving compositions described above, these compositions do not substantially enhance, and in some cases actually reduce, the fire retardancy of such wood products.
In U.S. Pat. No. 1,959,966, Robinson discloses a pressurization method for treating wooden building products, such as shingles. In his method, Robinson teaches the pressurized treatment of the wood material with sodium silicate, followed by a second pressure treatment with a weak acidic solution of ammonium sulphate to thereby form a reaction product of silicic acid disposed in the interstices of the wood.
In U.S. Pat. No. 963,810, Sala discloses a paint which is a flame retardant insoluble magnesium silicate surface coating for wood materials, the insoluble silicate being formed by first coating a surface of the wood with potassium silicate (silicate of potash) solution and thereafter applying a magnesium sulphate or magnesium chloride solution to thereby form the reaction product on the surface of the wood.
In U.S. Pat. No. 2,343,186, Hopkinson teaches fireproofing plasticizers consisting essentially of water insoluble metal salts.
Teachings similar to that described above with reference to the Robinson, Sala and Hopkinson patents are also included in the following U.S. Pat. Nos.: 1,271,506 to Ferguson; 2,420,644 to Athy et al: 1,643,116 to Felix; 671,548 to Gordon; 683,212 to Lacey; 3,281,318 to Stutz; 3,306,765 to DuFresne; and 3,663,355 to Shimizu.
Additionally, Chandler, in U.S. Pat. No. 1,994,752 teaches the in situ formation of the insoluble copper silicate in the ground about the wooden base of homes, the insoluble copper silicate being disclosed as toxic to many types of wood-destroying insects and pests.